Research supervisor, Ph.D., Sapa Vladimir, student, Assylkhanov Azamat

Kostanay State University A. Baitursynov, Kazakhstan

Advantages and disadvantages of solar energy

The sun is the source of life on planet Earth. One of the important characteristics of the solar radiation is the duration of sunshine.

Solar radiation is divided into three regions shortwave radiation: ultraviolet radiation with a wavelength λ < 0,4 microns - 9% intensity; electromagnetic (visible) radiation having a wavelength located in the range 0,4 < λ <0,7 microns - 45% intensity; infrared radiation having a wavelength λ > 0,7 microns - 46% intensity.

Atmosphere (ozone, water vapor and carbon dioxide) absorbed (absorb) certain solar radiation wave length. Significant weakening (decrease) in most of the ultraviolet and infrared regions of the spectrum is the result of absorption and causes the process of environmental impact on the Earth's climate.

Surface perpendicular to the incident radiation from direct sunlight, usually has the highest intensity of radiation. Since the distance from the Earth to the Sun varies throughout the year within 150 million. Km, the amount of solar radiation also varies from 1325 to 1420 W / m².

The sun's rays carry with them an inexhaustible flow of energy. They are always delivered to the ground more energy than we need today. The annual amount reaching the Earth solar energy is 1018 kWh, while the surface of the land accounts for about 20% of this energy.

Solar energy reaching the ground carries with it the heat evaporates water, forms a wind and water movement in the seas and oceans, and gives life to plants.

That solar energy, which is not directly absorbed in the world, is reflected into space. The earth is in a constant heat balance with its environment. If this does not happen, the Earth would be heated more and as a result of all life on it would have been impossible.

Solar energy resources are great, if not unlimited. The problem is that the largest amount of solar energy in the summer is supplied, i.e. at the time when the need for it is minimal.

In winter, when you need a lot of energy, the sun shines only a short time during the day, and then at a low angle. Only one way out: it is necessary to store energy in the summer and use it in the winter.

While solar energy is free and getting electricity from it is not always cheap enough. Therefore, experts continuously strive to improve solar cells and make them more efficient.

The main disadvantages of solar photovoltaic power plants are: the high cost of solar cells that convert solar radiation into direct current electricity; use inverters for converting DC electric power into AC electric power, reduce their efficiency; availability of batteries used as backup sources, and providing uninterrupted power supply to consumers, significantly increases the cost of solar power.

These drawbacks lead to the fact that currently the cost of electricity generated by solar photovoltaic power plants exceeds by several times the cost of electricity generated by traditional sources of electricity.

Solar power can be used to solve the energy problems of local and global problems of energy. With an efficiency of solar photovoltaic power plants 12% of all current electricity consumption in Kazakhstan can be obtained from these stations.

The most practical application in the world to a hybrid (combined) solar-fuel power plants with the following parameters: efficiency of about 14%, the steam temperature of 371 °C, the vapor pressure of 100 bar, the cost of electricity generated 0.08-0.12 USD / kWh.

The present level of production of solar cells corresponds to the initial phase of their use for lighting, water lifting, tele-communication stations, power household appliances in certain areas and in vehicles. The cost of solar cells is 2.5 - 3 USD / W at a cost of 0.25 - 0.56 USD / kWh.

Since the unit cost of solar power does not depend on its size and power, in some cases it is advisable to modular placement of solar photovoltaic power plants on the roof of a village house, cottage, farm. The owner of the solar photovoltaic plant will sell electricity to the grid during the day, and buy it from the power company to another counter at night. The advantage of such use, in addition to policies to promote small and independent power producers, is to save on the supporting structures and the land area, as well as combining the functions of the roof and an energy source.

Given that 1 kg silicon solar cell produces 30 years 300 MWh of electricity, it is easy to calculate the oil equivalent of silicon. Direct conversion of electric power of 300 MWh with the heat of combustion of oil of 43.7 MJ / kg gives 25 tons of oil per 1 kg of silicon. If we accept the efficiency of thermal power plants running on heavy fuel oil, 33%, then 1 kg silicon electricity generated is equivalent to about 75 tons of oil.

Due to the high reliability of the service life of solar photovoltaic power plants on the main components - and silicon solar cells can be increased to 50-100 years. This will require sealing technology excluding polymeric materials. The only limitation may be a need to replace them with more efficient ones. The efficiency of 25 - 30% is achieved in the production in the next 10 years. In case of replacement of silicon solar cells can be reused and the number of use cycles has no time restrictions.

References:

1. Yurchenko, A.V.; Savrasov F.W.; Yurchenko V. The real cost of energy - from resources to consumer // Bulletin of the Tomsk Polytechnic University. - 2009. - P. 43-46.

2. Stepanenko, N.I.; Gubin, V.E. Prospects for the use of alternative and renewable-energy sources in the conditions of Siberia // Modern Techniques and Technologies: Proceedings of IX Intern. Conf. students, graduate students and young scientists. - Tomsk, 2003. - T. 1. - P. 47-48.

3. Lukutin, B.V.; Surzhikova O.A.; Shandarova, E.B. Renewable energy in decentralized energy supply. - M .: Energoizdat, 2008. - 231 p.